1. Field of the Invention
The present invention relates to a communication apparatus that can communicate with an external apparatus, and further relates to a relevant control method and a computer-readable recording medium.
2. Description of the Related Art
There are many communication systems that are operable in conformity with High Definition Multimedia Interface (HDMI®) standard (hereinafter, referred to as “HDMI systems”). Each HDMI system includes a source device and a sink device. The source device transmits video data and audio data. The sink device includes a display device that is capable of displaying video data received from the source device.
The HDMI system enables each user to view desired video data on the display device of the sink device that can display video data reproduced from the source device.
Recently, control commands are usable to control a source device and a sink device that are present in an HDMI system. For example, a control command for the source device is usable to control the sink device. Similarly, a control command for the sink device is usable to control the source device.
If in the above-described HDMI system a user performs an operation instructing the source device to reproduce video data, the source device transmits a power control command to the sink device while reproducing the video data, so that a power source of the sink device can be activated to display the reproduced video data on the sink device.
As discussed in Japanese Patent Application Laid-Open No. 2007-202115, if the power source of the sink device is in an off state at the time when the power control command has been received from the source device, the sink device changes a state of the power source to an on state from the off state.
The above-described source device, if transmission of the power control command to the sink device is completed, transmits the reproduced video data to the sink device. If the sink device is in a state where the video data received from the source device is displayable, the sink device displays the video data received from the source device.
However, according to the above-described conventional system, even in a case where the sink device cannot receive any control command from the source device, the source device transmits the power control command to the sink device unconditionally in response to the operation instructing the source device to reproduce video data and then transmits the reproduced video data to the sink device.
Further, in a case where the sink device cannot be controlled based on the power control command received from the source device or in a case where the sink device cannot display any video data received from the source device, the source device repeats the above-described operation for transmitting the reproduced video data to the sink device.
As described above, the source device may continue the process for transmitting the video data to the sink device regardless of the state of the sink device. In such a case, a user who intends to view video data reproduced by the source device on the sink device may miss the opportunity to view a desired part of the reproduced video data.